The studies proposed here will contribute to our understanding how the central nervous system controls limb movement. More specifically, the long term objective is to provide a testable working hypothesis for the function of a major part of the motor system: the cerebellum. The experimental approach proposed in this application will be multidisiplinary. Information contained in the electrical signals transmitted by individual neural elements in the cerebellar cortex will be correlated with forelimb movement of monkey subjects. Parellel neuroanatomical tracing studies will provide information concerning the spatial distribution of pathways involved in the transmission of afferent information to the cerebellar cortex. Single neuron recording of mossy fibers, the major input to the cerebellum, provides a means of defining the type of signals conveyed to the cerebellum from a variety of sources within the nervous system. For example, in order to be able to generate visually guided movements, visual information needs to be integrated with motor commands that are sent to limb muscles to produce movement. The cerebellum is a prime candidate for the site of integration of sensory and motor signals. By defining the information content of the input signals and comparing these signals with those of cerebellar output neurons during identical behavioral tasks, I will assess the processing of signals along the path of information flow through the cerebellum. This basic information concerning the control mechanisms of the cerebellum is needed to obtain insights into cerebellar diseases that lead to dysmetria, a movement disorder characterized by the inability to produce goal directed movements in space and time without feedback information.